Self contained breathing apparatus, or SCBA, is a device worn by firefighters and rescue personnel to provide breathable air in an immediate danger to life and health situation. A SCBA typically has four main components: a high-pressure tank, a pressure regulator, an inhalation connection and an electronics system, all affixed together and mounted onto a carrying frame. SCBA's are one of the most important items of personal protective equipment used by firefighters and rescue personal. SCBA's allow firefighters to enter hazardous environments to perform essential interior operations including offensive fire attacks, victim search, rescue and removal, ventilation, and overhaul. They are also used at non-fire incidents involving hazardous material and confined spaces where there is a threat of toxic fumes or an oxygen-deficient atmosphere. A SCBA may fall into one of two different categories: an open circuit or a closed circuit SCBA.
SCBA systems used in firefighting places an emphasis on quality of materials required for heat and flame resistance above that of manufacturing cost. SCBA systems tend to be expensive because of the exotic materials used to provide heat and flame resistance and, to a lesser extent, to reduce the weight penalty on the firefighter. In addition, modern SCBA's incorporate a PASS (Personal Alert Safety System) device or an ADSU (Automatic Distress Signal Unit) into their design. These units emit distinctive high pitched alarm tones to help locate firefighters in distress following automatic activation if movement on the part of the firefighter is not sensed for a certain length of time. In addition to the PASS and ADSU units, SCBA's have been equipped with a Black Box for data logging, microphones for in-mask firefighter to firefighter communication, a telemetry system, and thermal imaging cameras to help the firefighter see through the smoke.
There have been several documented incidents where a SCBA failure may have been a contributing factor in the deaths of or injuries to firefighters. These incidents, coupled with a recognition of the importance of self contained breathing apparatus safety, prompted the U.S. Fire Administration to undertake various studies to address the many operational trends associated with SCBA failure incidents and to identify potential problems requiring correction or standardization. Equipment of such importance warrants close scrutiny. How much change is necessary and to what extent it will help a fire service must be asked. Standards and testing procedures have been changed over time to address problems that led to equipment failures and to ensure that SCBA's are more durable and reliable. As regular inspection, upgrade, and preventive maintenance will lessen the potential for catastrophic failures of a SCBA, standards for such were established in the National Fire Protection Association (NFPA) 1981 specification and NFPA 1982 specification, 2013 edition.
There have been several issues and operational failures that are frequently identified in SCBA maintenance and user training manuals and exercises. One of the most common is the failure to use the SCBA system correctly. Even with current emphasis on firefighter health and safety, and the expanding knowledge of the hazard posed by the products of combustion, some firefighters still fail to use SCBA during interior operations in smoke filled environments, especially during cases of salvage and overhaul. Injuries or even death can thus be avoided by continuing to educate firefighters about the risk involved from failure to use a SCBA. As a result, creating an easy to use, comfortable, and cost-efficient SCBA system is a very important consideration for manufacturers.
Another concern is hardware reliability, including battery failure. SCBA's are to be tested and certified according to the requirements set forth by the NFPA 1981 specification, entitled the Standard for Open Circuit Self Contained Breathing Apparatus. This ensures that SCBA's are extremely durable and rugged. If the SCBA is properly used and maintained by well-trained personnel, it should provide years of trouble-free service with little potential for hardware failure. However, battery failure is an all-to-common occurrence and the NFPA has required specific protocols, such as the PASS and ADSU (discussed above), to help prevent such failures. Lastly, some failures of the SCBA system may not directly result in death or injury, but may reduce efficiency and hamper firefighter performance. This type of failure is relatively common and most often attributable to operator error, physical abuse/neglect to the system, or inadequate preventive maintenance procedures. Examples include: difficult or slow donning of SCBA due to lack of familiarity or infrequent practice; free flowing regulators; O-rings blown out during cylinder changes; and improperly connected hoses or regulators. Below are some specific SCBA system failures not yet addressed.
On the average in the United States, most fire departments use their SCBA less than one-half hour per day. Thus for more than 23 hours per day, the SCBA is typically left dormant. When firefighters respond to a call time is of the essence, adrenaline is flowing, and tensions are high. With this fully understood, NFPA does not permit SCBA equipment to be equipped with an ON/OFF switch. Instead some automated detection means must be employed. Presently, most SCBA systems include a microcontroller that is programmed to monitor the air tank pressure during periods when the SCBA is inactive. With this the SCBA system can be made to turn on automatically within a few seconds after the air tank valve is opened and an increase in pressure is detected. Unfortunately, to save battery life, most SCBA systems program the microcontroller to enter a Sleep Mode function during periods of inactivity, typically scheduling it to wake up every few seconds to check air tank pressure. This method causes the Sleep Mode function to consume approximately 40% of the total SCBA battery life, which can lead to battery failure and possible malfunction during use, thereby compromising firefighter safety.
Additionally, under low voltage battery conditions the SCBA electronics operation can malfunction. NFPA electronics requirements demand that SCBA electronics determine the capacity of the SCBA battery power supply and report if it is insufficient for proper use. NFPA requires that the SCBA warn the firefighter of a low battery condition no later than when the batteries can provide just enough energy for the SCBA to function continuously for 2 hours in ‘Alarm Mode’. In order to maintain safe operation, it is important to be able to determine the condition or ‘health’ of the batteries, to be able to estimate the remaining battery life in ‘Alarm Mode’, and to provide a ‘Change Battery’ warning at the appropriate time. A test battery load current and battery load voltage measurement is employed to predict the remaining power reserves in the SCBA equipment. The battery test load current must be similar to the actual SCBA battery load. The traditional test for battery condition employs a fixed battery load resistor turned on and off by the circuit, while measuring the SCBA battery voltage change resulting from current draw. Using derived unit of electrical resistance law (ohm), an ohm value of the battery test load resistor must be selected to ensure that the low battery voltage current test load is similar to the actual SCBA load at that voltage. A fixed value battery load resistor with variable battery voltage allows for generation of a battery test load current at high voltage levels that can be unnecessarily excessive. Thus, a power conserving solution which employs a constant current battery test load where no power is wasted at high battery voltage levels would conserve SCBA battery life during battery load testing.
The most common electromagnetic interference (EMI) resistance circuit methods employ shielding, low source impedance and protection devices to mitigate the effects of EMI. The disadvantage of the low source impedance technique is that the amount of power required to protect the circuit increases with protection levels, therefore the lower the impedance of the circuit the greater the EMI protection level and power consumed. Again, battery consumption can be compromised. What is needed is a power conserving EMI circuit that changes the impedance of the circuit from low impedance high protection when the SCBA electronics is sleeping to high impedance low power when awake in order to conserve battery power.
NFPA requires a Black Box with SCBA for data logging, i.e. the SCBA electronics must record and time-stamp alarm conditions and certain other specified events. The data logs provide forensic information in the event of an accident occurring during operation of the SCBA. Clearly, having an accurately recorded time-stamp is important. Existing SCBA systems typically employ a real-time clock (RTC) to provide the time-stamp. The event data and the time-stamp are stored in non-volatile memory. Unfortunately, an RTC failure can cause the time-stamp to be lost, typically rendering the logged data useless for forensic purposes. Currently RTC failure experienced with a SCBA systems results in the time-stamp date being reverted to the RTC “default” date, which is not an accurate representation of the actual time of the event.
NFPA requires that a Personal Alert Safety System (PASS) device enters Pre-Alarm Mode if a firefighter is detected to be motionless for 20 seconds. The PASS piezo emitter must generate an NFPA specified sound in Pre-Alarm Mode. If the firefighter continues to remain motionless for an additional 12 seconds, the PASS must enter Alarm Mode and generate an NFPA specified universal alarm sound for the firefighter and perhaps more particularly for others, to hear continuously thereafter until the PASS piezo is turned OFF manually, indicating that the firefighter has depressed the Reset Button in response to the alert. Most SCBA manufacturers equip their PASS devices with an accelerometer to detect motion and include a piezo emitter and/or a volume acoustic speaker (VAS) in their PASS device housing. Presently, a problem/safety issue can occur when, under certain circumstances, vibrations generated by the piezo or speaker are transmitted through the PASS device housing causing interference with the operation of the accelerometer. Specifically, when the PASS enters Pre-Alarm Mode due to lack of movement for 20 seconds, the piezo commences emitting sound, which causes vibrations. These vibrations are transmitted through the housing and are detected by the accelerometer. The accelerometer sends a signal to the Microcontroller that it is detecting vibrations. The Microcontroller interprets the vibrations as movement by the firefighter, which turns OFF the piezo, and resets the 20-second clock. Unfortunately, this can lead to valuable rescue time being lost should the firefighter be in actual peril and, in a worst case scenario, can lead to possibly deadly consequences.
A major use of SCBA systems is for Search and Rescue (SAR) operations. When firefighters are operating in hazardous environments their vision is often completely obscured by smoke. This greatly limits their ability to locate victims at the scene. The standard procedure under these conditions is for the SAR team to crawl along the floor of the search area using their hands to manually perform the search. They must keep their legs linked together during the search so that they do not lose track of their team members. This is a slow, dangerous and inefficient process. Using a thermal imaging system to view the search area would provide a vast improvement in the search process. With a thermal imaging system obstacles and victims in the search area would be visible regardless of the amount of smoke. The search area could be quickly scanned, greatly reducing the search time and greatly increasing the likelihood that the victim can be saved.
The most commonly available thermal imaging systems are currently handheld units consisting of a thermal imaging camera (TIC) with an integrated display module. These units are a great help in firefighting and SAR operations. However, handheld TIC's have several disadvantages. Thick smoke between the display and the firefighter's facemask can make the display un-viewable. If the firefighter tries to compensate by moving the display up close to his facemask, his eyes may not be able to focus and the display becomes illegible. Since the display is typically the most heat-sensitive part of a handheld TIC, it must be insulated/shielded and constructed with expensive materials that can withstand the extreme temperatures and conditions inside a burning building. Consequently, handheld TIC's are very expensive so most fire departments can only purchase a limited number. Additionally, handheld TIC's tie up one of the firefighter's hands, which prevents him from doing other important work, such as carrying a victim or holding a firehose and directing water at a fire. These disadvantages limit the usefulness of handheld TIC's in firefighting and SAR operations.
A thermal imaging system with an SCBA facemask-mounted TIC and a display module mounted inside the firefighter's SCBA facemask would be a much more useful system in firefighting and SAR operations. An SCBA facemask-mounted TIC provides several advantages over a handheld unit. Both of the firefighter's hands are freed up for other uses. The scene captured by the TIC automatically displays the area that the firefighter is looking at. Mounting the TIC display module inside the SCBA facemask also has several advantages: the display can never be obscured by smoke; the display is protected from the external environment so it does not need any elaborate, expensive shielding, and it can be positioned so as not to obstruct the firefighter's forward field of view when not in use. Finally, the external TIC mounting bracket can also be designed to allow the TIC to be easily removed so that it could be shared between team members. This would allow flexibly in the assignment of firefighting and/or SAR team members and reduce costs for fire departments. An SCBA facemask-mounted TIC would provide each firefighter with a window through the smoke, to be able to perform his work hands-free, and to more easily locate victims.
One of the most common causes of death of firefighters is the inability to find their way out of a burning building. Firefighters usually perform their work in smoke that is so thick that visibility is virtually non-existent. When entering a building, firefighters will typically choose a left-hand search pattern or right-hand search pattern, feeling their way along the walls. If a firefighter gets separated from his partner, lost, disoriented or on the verge of heat-stroke, an SCBA facemask-mounted TIC would provide him with a window through the smoke, to be able to find his way out of the burning building.
Larger fires have an appointed Rapid Intervention Team (RIT) or Rapid Intervention Crew (RIC). The RIT or RIC typically consists of two or three firefighters whose mission is to rescue downed firefighters, for example, firefighters who are injured or who are trapped inside the fire. Time is of the essence for the RIT team. The team must locate the incapacitated or trapped firefighter before he runs out of air. An SCBA facemask-mounted TIC would enable the RIT team to find their incapacitated or trapped colleague much more quickly, greatly increasing the likelihood that the downed firefighter can be saved.
Recent prior art attempts at mounting a TIC on the firefighter's helmet or on the SCBA facemask have typically incorporated the display into the TIC housing. This method results in a bulkier configuration which can become an entanglement hazard for a firefighter operating in confined spaces. Additionally, whenever the display is external, thick smoke and/or soot collected on the outside of the mask can prevent the firefighter from being able to see the image, thereby negating the usefulness of the device.
The faceplates of SCBA facemasks are designed to shield firefighters by reflecting heat and are therefore not transparent to infrared (IR) light. Recent prior art attempts at mounting a TIC with a projector display inside the SCBA facemask have several drawbacks. The first disadvantage is the requirement of cutting apertures in the front of the facemask to allow the IR radiation to penetrate the shield, then covering the apertures with an IR transmissive material. This compromises the integrity that a continuous facemask provides and will not be considered acceptable by most fire departments and firefighters. Additionally, thermal imaging cameras generate a large amount of heat. Placing the thermal imaging camera inside the SCBA facemask would generate too much heat to be able to be worn by the firefighter for long enough to perform his mission. Also, current thermal imaging camera and projector display technology is too bulky to fit both components inside currently manufactured NFPA-approved SCBA facemasks.
Firefighters depend on the air in their SCBA air tank for life safety. They must always consider the amount of air it will take them to get to the exit of the burning or smoke-filled building, to assure that they do not run out of air, which could be fatal. Therefore, firefighters need to be continuously aware of the exact air tank pressure remaining in their air tank. What is lacking in the prior art is the ability to superimpose air tank pressure and other sensor readings on the HUD image viewed by the firefighter.
The prior art U.S. Pat. No. 7,298,535 Digital Situation Indicator (Kuutti) teaches a HUD that calculates the number of minutes of air time remaining. The instant invention improves upon the Digital Situation Indicator by superimposing the air time remaining onto the image transferred to the HUD Module by the TIC Module and viewed by the firefighter.
Burning buildings can be noisy places. Powerful jets of water are typically being sprayed through hoses, structures may be collapsing, and PASS alarms may be activating. Audio communications may be hampered by these noisy conditions. The instant invention allows the Incident Commander (IC) on the outside of the fire to send vital telemetry communications to the TIC-HUD, which will superimpose text on the HUD image viewed by the firefighter. These telemetry communications can be texts such as ‘Evacuate’ (EVAC) or Personnel Accountability Report (PAR). They can also be graphic such as the layout of the interior of a warehouse building or manufacturing plant. If a graphic image is transmitted via the telemetry system to the TIC-HUD, the firefighter will be able to view the image on the HUD display. What is lacking in the prior art is the ability to display telemetry communication images on the HUD display, and to superimpose text over the image displayed by the HUD Module and viewed by the firefighter.
In order to lead effectively, the Incident Commander on the outside of the fire needs to know what is going on inside the fire. The instant invention allows firefighters to transmit, through the TIC-HUD connection to the SCBA's telemetry system, thermal images or video taken by the thermal imaging camera. The IC can then make better, more informed decisions. For example, if the thermal images or video transmitted to the IC indicate that the fire is raging out of control, the IC can make the decision to go defensive and order all firefighters to evacuate (EVAC).
The TIC Module of the instant invention, in all embodiments, is mounted to the outside of the SCBA facemask, typically with a snap-in fitting. This allows the TIC Module, which is the most expensive component, to be shared and used by several firefighters on different shifts. Since the facemasks themselves are fit-tested and personal to each firefighter, upon finishing his shift, a firefighter can simply unsnap the TIC Module from his mask and allow the firefighter on the incoming shift to use it.
Thus, what is lacking in the prior art is a self contained breathing apparatus electronics system having sophisticated individual modules to alleviate the potential for such problems and maximizing battery life and providing a TIC-HUD with the TIC Module mounted externally and the HUD Module mounted inside the SCBA facemask, through which the firefighter can view thermal images transferred from the TIC Module, superimposed with sensor readings from the central SCBA electronics system or text communications from the Incident Commander, with an integrated microphone and ambient light sensing technology to automatically change the brightness of the display, with a quick-disconnect means to attach the TIC Module to the SCBA facemask, a means to incorporate audio speech detection circuitry to interpret and perform voice commands by the firefighter, and a means to transmit thermal images or video from the thermal imaging camera to the Incident Commander outside the fire.